kvm.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Peter Zijlstra <peterz@infradead.org>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Ingo Molnar <mingo@elte.hu>,
	the arch/x86 maintainers <x86@kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Nick Piggin <npiggin@kernel.dk>, Avi Kivity <avi@redhat.com>,
	Marcelo Tosatti <mtosatti@redhat.com>, KVM <kvm@vger.kernel.org>,
	Andi Kleen <andi@firstfloor.org>,
	Xen Devel <xen-devel@lists.xensource.com>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Subject: Re: [PATCH RFC V5 00/11] Paravirtualized ticketlocks
Date: Thu, 13 Oct 2011 12:54:05 +0200	[thread overview]
Message-ID: <1318503245.24856.12.camel@twins> (raw)
In-Reply-To: <cover.1318466916.git.jeremy.fitzhardinge@citrix.com>

On Wed, 2011-10-12 at 17:51 -0700, Jeremy Fitzhardinge wrote:
> 
> This is is all unnecessary complication if you're not using PV ticket
> locks, it also uses the jump-label machinery to use the standard
> "add"-based unlock in the non-PV case.
> 
>         if (TICKET_SLOWPATH_FLAG &&
>             unlikely(static_branch(&paravirt_ticketlocks_enabled))) {
>                 arch_spinlock_t prev;
> 
>                 prev = *lock;
>                 add_smp(&lock->tickets.head, TICKET_LOCK_INC);
> 
>                 /* add_smp() is a full mb() */
> 
>                 if (unlikely(lock->tickets.tail & TICKET_SLOWPATH_FLAG))
>                         __ticket_unlock_slowpath(lock, prev);
>         } else
>                 __add(&lock->tickets.head, TICKET_LOCK_INC, UNLOCK_LOCK_PREFIX); 

Not that I mind the jump_label usage, but didn't paravirt have an
existing alternative() thingy to do things like this? Or is the
alternative() stuff not flexible enough to express this?

  parent reply	other threads:[~2011-10-13 10:54 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-10-13  0:51 [PATCH RFC V5 00/11] Paravirtualized ticketlocks Jeremy Fitzhardinge
2011-10-13  0:51 ` [PATCH RFC V5 01/11] x86/spinlock: replace pv spinlocks with pv ticketlocks Jeremy Fitzhardinge
2011-10-13  0:51 ` [PATCH RFC V5 02/11] x86/ticketlock: don't inline _spin_unlock when using paravirt spinlocks Jeremy Fitzhardinge
2011-10-13  0:51 ` [PATCH RFC V5 03/11] x86/ticketlock: collapse a layer of functions Jeremy Fitzhardinge
2011-10-13  0:51 ` [PATCH RFC V5 04/11] xen: defer spinlock setup until boot CPU setup Jeremy Fitzhardinge
2011-10-13  0:51 ` [PATCH RFC V5 05/11] xen/pvticketlock: Xen implementation for PV ticket locks Jeremy Fitzhardinge
2011-10-13  0:51 ` [PATCH RFC V5 06/11] xen/pvticketlocks: add xen_nopvspin parameter to disable xen pv ticketlocks Jeremy Fitzhardinge
2011-10-13  0:51 ` [PATCH RFC V5 07/11] x86/pvticketlock: use callee-save for lock_spinning Jeremy Fitzhardinge
2011-10-13  0:51 ` [PATCH RFC V5 08/11] x86/pvticketlock: when paravirtualizing ticket locks, increment by 2 Jeremy Fitzhardinge
2011-10-13  0:51 ` [PATCH RFC V5 09/11] x86/ticketlock: add slowpath logic Jeremy Fitzhardinge
2011-10-13  0:51 ` [PATCH RFC V5 10/11] xen/pvticketlock: allow interrupts to be enabled while blocking Jeremy Fitzhardinge
2011-10-13  0:51 ` [PATCH RFC V5 11/11] xen: enable PV ticketlocks on HVM Xen Jeremy Fitzhardinge
2011-10-13 10:54 ` Peter Zijlstra [this message]
2011-10-13 16:44   ` [PATCH RFC V5 00/11] Paravirtualized ticketlocks Jeremy Fitzhardinge
2011-10-14 14:17     ` Jason Baron
2011-10-14 17:02       ` Jeremy Fitzhardinge
2011-10-14 18:35         ` Jason Baron
2011-10-14 18:38           ` H. Peter Anvin
2011-10-14 18:51             ` Jeremy Fitzhardinge
2011-10-14 19:02           ` Jeremy Fitzhardinge
2011-10-17 14:58             ` Jason Baron
2011-10-14 18:37         ` H. Peter Anvin
2011-10-14 19:10           ` Jeremy Fitzhardinge
2011-10-14 19:12             ` H. Peter Anvin
2011-10-17 16:33     ` H. Peter Anvin

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1318503245.24856.12.camel@twins \
    --to=peterz@infradead.org \
    --cc=andi@firstfloor.org \
    --cc=avi@redhat.com \
    --cc=hpa@zytor.com \
    --cc=jeremy.fitzhardinge@citrix.com \
    --cc=jeremy@goop.org \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@elte.hu \
    --cc=mtosatti@redhat.com \
    --cc=npiggin@kernel.dk \
    --cc=torvalds@linux-foundation.org \
    --cc=x86@kernel.org \
    --cc=xen-devel@lists.xensource.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).